Polarized electromagnetic apparatus.



' No. 699,660, P'atnt'ed May .13, 1902..

F. B. 600K.

I POLARIZED ELECTROMAGNETIC APPARATUS.

(Application Med Aug. 29, 1899.) (No Model.) 2 Shea'ts$h eet 1.,

No. 699,660. Patented May l3, I902 F; B. 600K.

POLARIZED ELECTROMAGNETIC APPARATUS.

(Appliclition filed Aug. 29, 1899.) (No Model.) 1 2 Sheets-Shoat 2 FRANK B. COOK, OF CHICAGO, ILLINOIS.

POLARIZED ELECTROMAGNETIC APPARATUS.

SPECIFICATION forming part of Letters Patent No. 699,660, dated May 13, 1902. Application filed August 29, 1899. Serial No. 728,819. (No model.)

To all whom it may concern/.-

Be it known that I, FRANK B. COOK, acitizen of the United States of America, and a resident of Chicago, Cook county, Illinois, have invented certain new and useful Improvements in Polarized Electromagnetic Apparatus, of which the following is a specification. By reason of the peculiar application of my invention for the purpose I shall describe and illustrateit in connection with that class of apparatus known as polarized electric bells, which are generally used at the subscribers stations of a telephone system for signaling the subscriber to come to the telephone. My invention, as will appear, is not, however, confined to such an application.

In what are termed party-line circuits, to be hereinafter more particularly described, it has hitherto been necessary to wind the electromagnet-coils of the subscribers bells in such manner as to provide for high impedance, in order to prevent a short circuit of the talking-currents, and to accomplish this result it has been customary to wind the coils of the electromagnet with wire of a smaller cross-section and also increase the length of the core of the said magnet.

My invention consists in the provision of a magnetic conducting casing which surrounds the electromagnet, thereby afiordiug a means of'protection against fire should the coil of the electromagnet burn out and also providing by thecaddition of the casing increased impedance orself-ind uction suflicient to adapt the apparatus for use in a partyline circuit, or,in fact, for any circuit arrangement in which the electric bell is bridged across between the leads of the circuit while conversation is being carried on.

My invention has certain other objects in view; and it consists in certain other features about to be described, reference being now had to the accompanyingd raWings,in which- Fig. 2. Fig. 6 is a detail sectional View through the electromagnet-casing. Fig. 7 is a detail view showing an adjustable armature. Fig. 8 is a like View showing the end of the shell tapered. Fig. i) is a diagrammatic view of a party-line bridging system, showing my improved bellapparatus included in such a system.

My invention as an electric bell for telephone uses is what is known as a polarized bell, which consists of a permanent magnet and an electromagnet, the combined influence of which elements is brought to bear upon the bell-armature. The permanent magnets A and A are magnetically connected, respectively, to the-two parts B and B of the inclosing shell or casing for the electromagnet D by the non-magnetic screws to a, which pass through the supporting-frame D and secure the permanent magnets and two parts of the casing to the said frame. This frame D is seen red to the base D and supports the parts. The inclosing shell (designated generally at E) is of magnetic con- .ducting material and completely incloses the electromagnet, and as the core D of the electromagnet D is magnetically connected to the two parts B and B of this casing, Fig. 1, the core, the shell, and the armature form a nearly-complete magnetic circuit. The ringarmature H, Fig. 5, is pivoted or hinged at one side of or at a point beyond the side of the casing, as designated at b b, and encircles the electromagnet D. This armature is therefore'disposed between the ends of the two parts B and 15 0f the magnetic casing or shell, so that the polarized ends thereof act directly upon the armature. The bell-striker arm J, between the two bells J J is attached to and carried by the armatureH. Withan alternating current the ends of the two parts of the shell or casing are of different polarities, and a combined push and pull is brought to bear upon the armature. The ends of the permanent magnet, also brought to bear upon the armature H, are of the same relative polarity, thus permanently polarizing the armature with one magnetic polarity.

In Fig. 3 I have shown an attachment to be used when a straight current is employed which is capable of ready attachment to or detachment from the bell, consisting of a prolongation or extension-piece K of the armature, a bracket K removably held on the permanent magnets by the screws a a, having a holding-arm K a spring K, secured to the extension of the armature, and an adjusting-screw K for the spring. This device is capable of readyremoval and can be reversed in position as desired to exert an opposite pull on the armature when a current of opposite polarity is used.

It will be observed that the lines of force of the magnet-poles of the shell or casing act directly upon. the armature, and the whole arrangementis such as to produce a more sensitive action o the armature. This sensitiveness of action is obtainable particularly because of the close and intimate proximity of one part of the armature to the poles of the shell, which proximity is always maintained during the vibrations of the bellst-riker. To bring the armature in still closer proximity, the ends of the magnetic shell or casing may be tapered, as shown in Fig. 7, to afford space for the necessary vibration of the armature, and yet position a part of the armature near its pivot in still closer proximity to the poles of the shell. As shown in Fig. 7, the armature maybe formed in two parts which are adjustable toward and away from each other by the adj Listing-screw (Z in order to regulate the stroke of the armature. As the electromagnet is completely inclosed, should it burn out under an excessive current the communication of fire to other apparatus or to the building is avoided. The construction as a whole is compact.

In party-line systems such as illustrated in Fig. 9 the subscribers apparatus is bridged across between the leads 25 and 20 of the line-circuit from the central-office jack 27..

The electric bell 28 at each station is inclosed in a bridge 29 of its own, and the generator 30 and receiver 31 and transmitter 32, constituting the telephone set, are connected in series with each other in another bridge, as shown, and in parallel with the electric bell. In such an arrangement as stated it is necessary that the electric bell should be of high impedance or self-induction in order to prevent the voice-currents from short-circuiting across the bridge 29. This high impedance o1- self-induction is obtained in myinvention by the magnetic conducting shell or casing about the elcctroniagnet, and it is therefore unnecessary to increase the size of the electromagnet to accomplish this desired end. So, also, in any instance where the bell is bridged between the leads of the circuit the construction and apparatus of my invention in and of itself affords the necessary impedance or self-induction.

It is evident that the armature itself may be a permanent magnet, and thus be polarized.

Having thus described myinvention, what I claim as new therein, and desire to secure by Letters Patent, is-

1. In a polarized electromagnetic apparatus the combination of a polarized and pivoted armature, a two-part magnetic casing or shell, said armature being positioned between the ends of the two part shell and said casing or shell surrounding the electromagnet.

2. In a polarized electromagnetic apparatus, the combination of a polarized and pivoted armature, a two-part magnetic casing or shell, said armature encircling the electromagnet and positioned between the ends of the shell and said shell surrounding the electromagnet.

3. An electromagnetic apparatus, consisting of an armature, a two-part magnetic shell or casing, an extension of said armature, a bracket and a spring connected with the armature and bracket, together with means for regulating the tension of the spring.

4. In a polarized electromagnetic apparatus the combination. of a polarized and pivoted armature, a two-part magnetic casing or shell having a tapered end or index, said armature being positioned between the ends of the two-part shell and said casing or shell surrounding the electromagnet.

5. In a polarized electromagnetic apparm tus, the combination of a polarized and pivoted armature, a two-part magnetic shell, and a divided armature positioned between the ends of the casing or shell and means foradjusting the parts of the armature in relation to said ends, the said casing or shell surrounding the electromagnet.

Signed by me at Chicago, Cook county, Illinois, this 26th day of August, 180.).

FRANK 13. 000K.

\Vilnesses:

CHAS. O. BULKLEY, L. M. BULKLEY.

IOC 

